How did China learn the technology of steel intaglio carving?

In the process of preparation, the branch printing bureau is building a factory building and recruiting personnel for technical training. In particular, Bi Chennian, Li Fu, Yan Xilin, Wu Jintang, etc., who were recruited from Tianjin Official Newspaper Bureau and had studied copper intaglio carving technology from the Japanese, are worth mentioning. After a period of study, they all mastered the steel intaglio carving technology and became the first generation of steel intaglio carving technicians in China, which attracted the attention of the printing industry at that time and laid a solid foundation for the further development of steel intaglio carving technology in China.